I guess what I am wondering is, I have a ING account, and it just seems to me that it grows very slowly, and I also have a TSP and the employer contribute to it as well, and that one is growing pretty nicely, so, I guess I was wondering if I should consider the notion of opening another retirement plan as well?

It won't hurt anything, but the limits are the same no matter whether you invest it in 1 account or 50.

Just keep an eye on the fees. I'm not really knowledgable to help you in that regard.